Field of Invention
The invention generally relates to self-opening, collapsible, foldable and shortentable umbrellas.
The invention relates, more particularly to a self opening umbrella having canopy-supporting rods, which can be shortened in at least a twofold manner; and a stick which is telescopic in at least two stages and carries a displaceable slider, to which lower struts of a canopy linkage are linked. The frame is opened by a compression spring working axially of the stick between two relatively movable parts and is closed by pulling the slider down the stick against the action of the spring.
A self opening umbrella of this kind is collapsible and shortenable and thus, one of the pocket type, as, for example, known from the U.S. Pat. No. 4,676,262. In this model, the drive spring is located directly under the umbrella crown, which is fixed on the stick; and it acts upon an auxiliary slider. Since the displacement path of this spring below the umbrella crown is relatively short when opening and closing the umbrella, the stick is largely unaffected by wear-erosion and scratches in contrast to self opening umbrellas of other models, for example, in which the drive spring is disposed between main and auxiliary sliders, and moves up and down over almost the entire stick length when opening and closing the umbrella. Nevertheless, in both constructions the drive spring requires a relatively high force when retracting the main slider during the closing movement and it is difficult for the user to maintain a grip on the slider and complete the closing movement of the slider down towards the handle at the lower end of the stick.